MMP9 and hepatocellular carcinoma: Naringenin possesses an anti-invasive effect against HCC cells via the inhibition of TPA-mediated MMP-9 expression, associated with inactivation of ERK1/2 and JNK1/2 pathways [33].Based on these observations, our results show that PA significantly suppressed the ERK1/2 signaling pathway, but not the JNK1/2 and p38 pathways.